1. Field of the Invention
The invention relates to a power converter module, more particularly to a power converter module with an active snubber circuit.
2. Description of the Related Art
A conventional power converter module 1 is shown in FIG. 1. The power converter module 1 includes a power transformer that has primary and secondary windings (n1) (n2), a power switch (S) connected in series with the primary winding (n1), a capacitor (C) connected across the power switch (S), and a forward rectifier 10 that interconnects the secondary winding (n2) to a load 2. The series combination of the primary winding (n1) and the power switch (S) is connected in parallel to a DC power source (Vin). When the power switch (S) operates at a high switching frequency, while the capacitor (C) is capable of absorbing voltage surges at the instant of switch closing, the surge energy is neither regenerated to the DC power source (Vin) nor provided to the load 2, which limits the conversion efficiency of the power converter module 1. With further reference to FIG. 2, based on experimental results, under the condition that DC power source (Vin) is 24V and load voltage (Vo) is 12V, the conversion efficiency (xcex7) of the conventional power converter module 1, when output current (Io) is 2 A, is only 88%.
Therefore, the object of the present invention is to provide a power converter module that can regenerate surge energy so as to improve the conversion efficiency.
According to the present invention, a power converter module comprises a power transformer, a first power switch, and an active snubber circuit. The power transformer has a primary winding and a secondary winding adapted to be coupled electrically to a first load. The primary winding has first and second terminals connected electrically and respectively to first and second nodes. The first power switch has a first switch terminal connected electrically to the second node, and a second switch terminal connected electrically to a third node. The first and third nodes are adapted to be coupled electrically to a power source. The active snubber circuit serves to recover surge energy, and includes a snubber diode, a snubber capacitor, a snubber transformer, and a second power switch. The snubber diode has a first diode terminal connected electrically to the first node, and a second diode terminal connected electrically to a fourth node. The snubber capacitor has a first capacitor terminal connected electrically to the second node, and a second capacitor terminal connected electrically to the fourth node. The snubber transformer has a primary winding and a secondary winding adapted to be coupled electrically to a second load. The primary winding has a first terminal connected electrically to the fourth node, and a second terminal connected electrically to a fifth node. The second power switch has a first switch terminal connected electrically to the fifth node, and a second switch terminal connected electrically to the third node.